Question: Simplify the following expression: $ x = \dfrac{-1}{6} + \dfrac{r - 9}{-2} $
In order to add expressions, they must have a common denominator. Multiply the first expression by $\dfrac{-2}{-2}$ $ \dfrac{-1}{6} \times \dfrac{-2}{-2} = \dfrac{2}{-12} $ Multiply the second expression by $\dfrac{6}{6}$ $ \dfrac{r - 9}{-2} \times \dfrac{6}{6} = \dfrac{6r - 54}{-12} $ Therefore $ x = \dfrac{2}{-12} + \dfrac{6r - 54}{-12} $ Now the expressions have the same denominator we can simply add the numerators: $x = \dfrac{2 + 6r - 54}{-12} $ $x = \dfrac{6r - 52}{-12}$ Simplify the expression by dividing the numerator and denominator by -2: $x = \dfrac{-3r + 26}{6}$